Newsgroups: comp.parallel.mpi
From: Kamran Kazemi <kamran@cs.uwa.edu.au>
Subject: Re: Process ranks in MPI_COMM_WORLD
Organization: The University Of Western Australia
Date: Mon, 06 Apr 1998 17:08:25 +0800
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Message-ID: <35289B89.4E264FB1@cs.uwa.edu.au>

Raja Daoud wrote:

> MPI_COMM_WORLD is created by MPI_Init() and its group cannot be changed
> by applications.

I am using MPI_Spawn_multiple to start the processes.  MPI2 specifies
that the ranks of the children is determined by the order of the binaries
in the call.  In my case it really does not matter which process gets which
rank.  The critical point is that the ranks must stay the same after
MPI_COMM_WORLD is created.  From your explanation this would bethe case.

>  Some implementations provide you with non-standard
> ways to control the mapping of (binaries, hosts) pairs to MPI_COMM_WORLD
> ranks at startup time, for example ordering the ranks following the
> application description syntax (e.g. appfile, appschema, procgroup file,
> or command-line arguments).

You said it, they are non-standard methods.  I am not trying to do any
mapping at all.  I just wanted to ensure that the ranks in MPI_COMM_WORLD
cannot be changed after its creation which is the case.

Thanks Raja.

Kamran